This proposal requests funds to enable U. S. scientists, particularly young investigators, postdoctoral fellows, and predoctoral students to attend the. Third International Positive-Strand RNA Virus Symposium in Clearwater, Florida, September 19-25, 1992. Symposium co-organizers are Margo A. Brinton, Georgia State University and Roland R. Rueckert, University of Wisconsin. The scientific program will be organized with the aid of a Program Committee. Session topics will be: viral Evolution; Genome Replication; Protein Translation, Cleavage and Modification; Virion Structure and Assembly; Viral Receptors, Virus-uptake and Disassembly; Antigenic Structure and Function; Molecular Aspects of Pathogenesis and Virulence; and Strategies for Control of Virus Disease. Positive strand RNA viruses are those whose genomes function as an mMRNA. At least seven families of animal viruses, the majority of the plant viruses, one family of insect viruses and one family of bacteriophages are of this type. Diseases caused by these viruses are of medical, agricultural, and economic significance. Human pathology resulting from positive-strand RNA virus infections includes encephalitis, poliomyelitis, heart disease, hepatitis, the common cold, gastroenteritis, hemorrhagic fever, and birth defects. Positive-strand RNA virus infectious are often fatal in patients immunosuppressed because of cancer, transplantation, or AIDS. The First International Positive-Strand RNA Virus Symposium was held under the auspices of the UCLA Symposium on Molecular and Cellular Biology in Keystone, Colorado in 1986 with approximately 250 participants. The second symposium was held in Vienna, Austria in 1989 with about 350 participants. Because of the broad-based international attendance of the symposium, the conference site alternates between the U. S. and Europe. Both the 1986 and 1989 meetings were extremely successful in achieving the goal of promoting discourse and scientific collaboration between animal, plant, and insect virus researchers.